I could be very wrong, but I believe maybe for the future release, for now (prior to 9.3), they are mutually exclusive, you either choose
a dynamic LIBNAME engine
Or
the SQL Pass-Through Facility
.
They are running on different rules. The former gives you the comfort of using SAS library, and SAS takes lots underline efforts to make you feel that you are dealing regular SAS tables. The latter could get you some performance edge if the database is optimized, but it is nothing more than a straight portal for you to deliver your compatible SQL code.
Haikuo